Kriega says:

Designed to be a perfect fit on the KTM 690, HUSQVARNA 701 & GASGAS 700 with a custom shape and specific fitting hardware. The OS-BASE is an 'over the seat harness' for mounting OS-6, OS-12, or OS-18 ADVENTURE PACKS as soft panniers, with no need for metal frames. This system provides a super-tough, lightweight carrying solution, with only slight bodywork alterations needed. The fitting hardware gives the flexibility to mount a one, two, or three-pack set-up, depending on your ride. The set-length straps make mounting quick and easy, and the custom shape provides a tight, secure fit with plenty of distance from the exhaust and fuel filler. It takes less than a minute to mount and just seconds to remove it.

BUYING OPTIONS
OS-BASE ONLY
OS-BASE COMBO 12 - OS-BASE KTM 690 PLUS 2 x OS-6 ADVENTURE PACKS
OS-BASE COMBO 24 - OS-BASE KTM 690 PLUS 2 x OS-12 ADVENTURE PACKS
OS-BASE COMBO 36 - OS-BASE KTM 690 PLUS 2 x OS-18 ADVENTURE PACKS

BODYWORK DAMAGE DISCLAIMER 
Even though most of the OS-BASE mounts on the seat, the sides can rub against the plastic side panels of the bike, resulting in minor abrasion. This can be further exaggerated if mud and dust get in between the OS-BASE and the plastics. We strongly recommend applying a clear adhesive protective sheet to where abrasion may occur on your motorcycle.